Intent to Extend Experiment: FedCM Button Mode API and Use Other Account API
Yi Gu
Contact emails
yi...@chromium.org, tanza...@chromium.org, cbies...@chromium.org,Explainer
https://github.com/w3c-fedid/active-modeSpecification
NoneSummary
We plan to experiment with two new extensions for the Federated Credential Management (FedCM) API:
Button Mode API
The button mode lets websites trigger FedCM directly when a user clicks a button (like a "Sign-in with IdP" button). This means FedCM will always display a visible user interface for login, in contrast to the widget mode where no UI is shown if a user’s login status is logged out.
When the FedCM API is used in "button mode" and a user isn't logged in, they'll be taken to the IdP login screen (in a pop-up window). Since this happens in response to a clear user action, the UI might even be more prominent (e.g., centered and modal) compared to the more subtle UI of widget mode.
Use Other Account API
With this API, an Identity Provider can request the browser to show a button that allows users to choose other accounts.
Button Mode API
The button mode lets websites trigger FedCM directly when a user clicks a button (like a "Sign-in with IdP" button). This means FedCM will always display a visible user interface for login, in contrast to the widget mode where no UI is shown if a user’s login status is logged out.
When the FedCM API is used in "button mode" and a user isn't logged in, they'll be taken to the IdP login screen (in a pop-up window). Since this happens in response to a clear user action, the UI might even be more prominent (e.g., centered and modal) compared to the more subtle UI of widget mode.
Use Other Account API
With this API, an Identity Provider can request the browser to show a button that allows users to choose other accounts.
Blink component
Blink>Identity>FedCMTAG review
https://github.com/w3ctag/design-reviews/issues/935TAG review status
PendingChromium Trial Name
FedCmButtonModeOrigin Trial documentation link
https://github.com/w3c-fedid/FedCM/blob/main/explorations/HOWTO-chrome.md#button-mode-apiWebFeature UseCounter name
kFedCmButtonModeRisks
Interoperability and Compatibility
These are extensions to the FedCM API. Apple and Mozilla have both expressed a positive opinion on the initial FedCM API [1]. They have not yet shipped but Mozilla is prototyping [2]. If a user agent chooses not to implement these extensions, the sign-in flow should not be affected in that user agent because developers can fallback to the existing federated sign-in mechanisms.
[1] https://groups.google.com/a/chromium.org/g/blink-dev/c/URpYPPH-YQ4/m/bzghj9N3AQAJ
[2] https://groups.google.com/a/mozilla.org/g/dev-platform/c/ncmUwK1uO98/m/COhPA4ZrAAAJ
Gecko: No signal
WebKit: No signal
Web developers: Positive (https://github.com/fedidcg/FedCM/issues/442) These features are being developed to address existing feedback for the FedCM API.
Other signals:
Activation
Similar to the FedCM API, we deliberately leave the bulk of the work to the IdP to ensure that minimal RP change is needed.
This feature, specifically, is one that can be currently controlled by IdP (via JS SDK for “button mode”, via server-side config for “use other account”), so we expect activation to have a similar profile as FedCM: immediately enabled to websites (without redeployment) by IdPs making use of it (by redeploying their JS SDKs).
Security
The button mode shares most of the security properties from the widget mode. e.g. honoring CSP, CORS, using security headers, not asking users to type in the browser UI etc.
It’s worth noting that the pop-up window has the same web platform properties as what one would get with window.open(url,””,”popup,noopener,noreferrer”) that loads the login_url. It is important to note that there's no communication allowed between the website and this pop-up (e.g. no postMessage, no window.opener). We have shipped LoginStatus API and Error API in FedCM that use this type of pop-up window.
WebView application risks
Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?
None
Goals for experimentation
Gather data on whether a browser mediated sign in flow on a critical user journey is well received by users and developers. We'd like to see how the proposed UI/API play out and iterate on them to ship the API in its best shape.
Reason this experiment is being extended
We have been addressing feedback on the API as well as the UI since the OT starts. Therefore we'd like to extend the OT to test the new changes and support partners to run further experiments.
Progress update per I2EE requirement:
- Draft spec: The Button Mode API (recently renamed to "FedCM Mode API") has advanced to stage 2 in Federated Identity Working Group which means that this work has received WG consensus to adopt the proposal as the basis for the work as a Working Draft. We are working on a spec PR at this moment.
- TAG review: Done in the initial I2E thread
- bit.ly/blink-signals requests: Done in the initial I2E thread
- Outreach for feedback from the spec community: Done in the initial I2E thread
- WPT tests: Done in the initial I2E thread
Ongoing technical constraints
None
Debuggability
No special support needed
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
NoFedCM in general is not supported in webview
Is this feature fully tested by web-platform-tests?
Yeshttps://wpt.fyi/results/fedcm/fedcm-button-and-other-account?label=experimental&label=master&aligned (They currently fail on wpt.fyi because the feature is off by default)
Flag name on chrome://flags
FedCmButtonMode, FedCmUseOtherAccountFinch feature name
kFedCmButtonMode
kFedCmUseOtherAccount
Requires code in //chrome?
TrueTracking bug
https://crbug.com/40284792Launch bug
https://launch.corp.google.com/launch/4293366Estimated milestones
| Origin trial desktop first | 125 |
| Origin trial Android first | 128 |
| Origin trial extension 1 end milestone | 130 |
| Origin trial extension 2 end milestone | 133 |
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/4689551782313984Links to previous Intent discussions
Intent to prototype: https://groups.google.com/a/chromium.org/g/blink-dev/c/hZg8ice8f0A/m/ubJPHUsDAwAJ
Intent to experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/bQqXXv2S9q0
Mike Taylor
Thanks LGTM to extend to 133 inclusive, given the progress on the proposal in the WG, and iteration on the API design/UI .
If you were to request another extension down the road, I would
expect to see further progress on the spec PR, and updated tests
to match.
thanks,
Mike
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